Bag opening apparatus and bag opening method

ABSTRACT

A bag opening apparatus and a bag opening method capable of efficiently opening a bag body in a short period of time are provided. A bag opening apparatus includes a gap formation unit which bends at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap. When a first press drive member presses a first holding unit against the front wall portion, a contact part of the first holding unit is swung against urging force of an urging part of the first holding unit to bend the front wall portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application Is based upon and claims the benefit of priority fromJapanese Patent Application No. 2017-208575, filed on Oct. 27, 2017; theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention is related to a bag opening apparatus and a bagopening method.

BACKGROUND ART

Conventionally, as apparatuses for opening the mouth portion of a bagbody, such as a package bag, apparatuses adopting various methods havebeen proposed. For example, according to a device using a suction cupfor opening a bag body, the suction cup is kept in contact with a bagsurface over a predetermined time until an appropriate negative pressureis formed between the suction cup and the bag surface, and then, thesuction cup is moved together with the bag surface so that the mouthportion is opened.

On the other hand, Japanese examined utility model (registration)application publication No. 3-22084 discloses an apparatus which opens aflat film tube without using a suction cup. In this apparatus, rollersforming a pair are once moved outward in the width direction in a stateof being in contact with a tube surface, and thereafter, the rollersforming a pair are moved inward in the width direction using the elasticforce of a spring while the rotation of each of the rollers isrestricted. As a result, the tube surface is dragged to the pair ofrollers moving Inward in the width direction, so that a gap is formed inthe mouth portion of the tube.

Further, Japanese patent application publication No. 2013-82487discloses an apparatus which opens a package bag made of paper, nonwovenfabric or the like. In this apparatus, a package bag is opened by movinga pair of conveyance claws in a closed state while a part of the packagebag is nipped between the closed conveyance claws.

SUMMARY OF INVENTION Technical Problem

In an opening device using a suction cup, a period of time for placingthe suction cup in a halt state is needed in order to make the suctioncup to suck a bag surface as described above. This period of timebecomes a bottleneck for speeding up the opening process of a bag body.In particular, when the opening process of a bag body is combined withanother process such as a packaging process, the period of time requiredfor the suction of a suction cup can be a major factor impedingimprovement of the performance of the whole processing.

In addition, in the apparatus disclosed in Japanese examined utilitymodel (registration) application publication No. 3-22084, prior toforming a gap in the mouth portion of a tube by moving a pair of rollersinward in the width direction, a preliminary operation which makes thepair of rollers move outward in the width direction is needed. Thispreliminary operation is also one of the factors hindering theimprovement of the processing performance. In particular, when it isnecessary to obtain a large gap formed in the mouth portion of a tube asin the case where the tube width is large, it is also necessary to makelarger the displacement amount of the tube. In this case, it isnecessary to increase the amount of inward movement of the pair ofrollers in the width direction; however, for this purpose, it isnecessary to increase the amount of outward movement of the pair ofrollers in the width direction in the preliminary operation, and thusthe time required for the processing is greatly increased. As describedabove, an apparatus and a method which need to perform the preliminaryoperation depending on the actual opening operation are not necessarilysuitable for high-speed processing.

Moreover, in the apparatus disclosed in Japanese patent applicationpublication No. 2013-82487, the conveyance claws forming two pairs (thatis, four conveyance claws) are alternately arranged in a state where apackage bag is positioned therebetween, and the package bag is bent andfolded in accordance with the shape of the conveyance claws. In thiscase, the package bag is gripped and opened by the conveyance claws in asharply folded state. Therefore, in a case where a package bag is openedby using the apparatus of Japanese patent application publication No.2013-82487, depending on the material of the package bag,folding/bending marks remain in the package bag and thus the aestheticappearance and the quality of the package bag are impaired.

Furthermore, in the apparatus of Japanese examined utility model(registration) application publication No. 3-22084 and the apparatus ofJapanese patent application publication No. 2013-82487 described above,the action direction of the holding members (specifically, a pair ofrollers or a pair of conveyance claws) for bringing the holding membersinto contact with a bag surface and the action direction of the holdingmembers for opening a bag body are opposite to each other. Thus,compared to a case where the action direction of the holding members forbringing the holding members into contact with a bag surface is the sameas the action direction of the holding members for opening the bag, theopening operations of the apparatuses disclosed in Japanese examinedutility model (registration) application publication No. 3-22084 and theopening of the device of Japanese patent application publication No.2013-82487 are inefficient.

The present invention has been contrived in view of the abovecircumstances, and an object thereof is to provide an apparatus and amethod capable of efficiently opening a bag body in a short period oftime. Another object of the present invention is to provide an apparatusand a method capable of opening a bag body while preventing foldingmarks from being formed on the bag body.

Solution to Problem

One aspect of the present invention is directed to a bag openingapparatus comprising a gap formation unit which bends at least a frontwall portion, of the front wall portion and a back wall portion thatconstitute a mouth portion of a bag body, so as to form a gap betweenthe front wall portion and the back wall portion, wherein: the gapformation unit includes a first holding unit and a first press drivemember which moves the first holding unit between a position where thefirst holding unit is separated from the front wall portion and aposition where the first holding unit is pressed against the front wallportion, the first holding unit includes a contact part, a support partwhich swingably supports the contact part, and an urging part whichurges the contact part via the support part, and when the first pressdrive member presses the first holding unit against the front wallportion, the contact part is swung against urging force of the urgingpart while the contact part is in contact with the front wall portion soas to bend the front wall portion.

The gap formation unit may further include a second holding unit; thefirst press drive member may move not only the first holding unit butalso the second holding unit between the position where the firstholding unit and the second holding unit are separated from the frontwall portion and the position where the first holding unit and thesecond holding unit are pressed against the front wall portion; and whenthe first press drive member presses the first holding unit and thesecond holding unit against the front wall portion, the contact part ofthe first holding unit may be swung so as to approach the second holdingunit while the contact part of the first holding unit is in contact withthe front wall portion.

The second holding unit may include a contact part, a support part whichswingably supports this contact part, and an urging part which urgesthis contact part via the support part; and when the first press drivemember presses the first holding unit and the second holding unitagainst the front wall portion, the contact part of the second holdingunit may be swung against urging force of the urging part of the secondholding unit so as to approach the contact part of the first holdingunit while the contact part of the second holding unit is in contactwith the front wall portion.

The bag opening apparatus may further comprise an air blowing unit whichejects air toward the gap.

The gap formation unit may further include: a third holding unit and afourth holding unit; and a second press drive member which moves thethird holding unit and the fourth holding unit between a position wherethe third holding unit and the fourth holding unit are separated fromthe back wall portion and a position where the third holding unit andthe fourth holding unit are pressed against the back wall portion; andin a state where the contact part of the first holding unit and acontact part of the third holding unit are opposed to each other via thefront and back wall portions and the contact part of the second holdingunit and a contact part of the fourth holding unit are opposed to eachother via the front and back wall portions, the first press drive membermay press the first holding unit and the second holding unit against thefront wall portion, and the second press drive member may press thethird holding unit and the fourth holding unit against the back wallportion.

The gap formation unit may further include a receiving part which aredisposed on a side of the back wall portion and has a receiving surfacefacing the back wall portion; and the first press drive member may pressthe first holding unit against the front wall portion in a state wherethe front wall portion and the back wall portion are sandwiched by thefirst holding unit and the receiving surface.

The receiving part may include a first elastic member forming thereceiving surface.

The first holding unit may include: a first link which is attached tothe first press drive member and swingably supports one side of thesupport part of the first holding unit, and a second link which isattached to the first press drive member so as to be capable of movingback and forth and swingably supports another side of the support partof the first holding unit; and when the first press drive member pressesthe first holding unit against the front wall potion, the urging part ofthe first holding unit may urge the contact part of the first holdingunit, via the second link and the support part of the first holdingunit, in a direction including a component of a direction opposing adirection in which the contact part of the first holding unit is swung.

The contact part may include a second elastic member.

The bag opening apparatus may further comprise a pair of grippers whichholds both side portions of the bag body, wherein before or while thefirst press drive member presses the first holding unit against thefront wall portion to cause the contact part of the first holding unitto swing, at least one of the grippers is moved in such a manner that adistance between the grippers is reduced.

Another aspect of the present invention is directed to a bag openingmethod causing a bag opening apparatus to bend at least a front wallportion, of the front wall portion and a back wall portion thatconstitute a mouth portion of a bag body, so as to form a gap betweenthe front wall portion and the back wall portion, wherein: the bagopening apparatus includes a gap formation unit having: a first holdingunit; and a first press drive member which moves the first holding unitbetween a position where the first holding unit is separated from thefront wall portion and a position where the first holding unit ispressed against the front wall portion, the first holding unit includesa contact part, a support part which swingably supports the contactpart, and an urging part which urges the contact part via the supportpart, and the bag opening method Includes a step of bending the frontwall portion by causing the first press drive member to press the firstholding unit against the front wall portion in such a manner that thecontact part is swung against urging force of the urging part while thecontact part is in contact with the front wall portion.

According to the present invention, a bag body can be efficiently openedin a short period of time. Further, according to the present invention,a bag body can be opened while folding marks are prevented from beingformed on the bag body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view illustrating a schematic configuration of a bagopening apparatus according to a first embodiment.

FIG. 2 is a process diagram of a bag opening method according to thefirst embodiment.

FIG. 3 is a process diagram of a bag opening method according to thefirst embodiment.

FIG. 4 is a process diagram of a bag opening method according to thefirst embodiment.

FIG. 5 is a plan view illustrating an example of a state of a bag bodywhich may occur in the apparatus and the method according to the firstembodiment.

FIG. 6 is a plan view illustrating a schematic configuration of a bagopening apparatus according to a second embodiment.

FIG. 7 is a process diagram of a bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from above.

FIG. 8 is a process diagram of the bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from above.

FIG. 9 is a process diagram of the bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from above.

FIG. 10 is a process diagram of the bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from the side.

FIG. 11 is a process diagram of the bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from the side.

FIG. 12 is a process diagram of the bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from the side.

FIG. 13 is a process diagram of the bag opening method according to thesecond embodiment, showing a state in which the bag opening apparatus isviewed from the side.

FIG. 14 is a plan view illustrating a schematic configuration of a bagopening apparatus according to a first modified example.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

In the following embodiments, bag opening apparatuses used in apackaging machine will be described as an example, but the bag openingapparatuses and bag opening methods described below may be applied toany mechanism using a bag body of which the mouth portion is opened. Apackaging machine typically includes, in addition to a bag openingapparatus, a device which introduces the contents into a bag bodythrough the opened mouth portion, a device which closes and seals themouth portion after the contents have been introduced into the bag body,and other devices. The form of the contents to be introduced into a bagbody is not limited, and it is possible to introduce contents in theform of gas, liquid, gel or solid or contents having two or more forms,into a bag body.

In a bag opening apparatus and a bag opening method according to theembodiment described below, first, the close contact between the frontwall portion and the back wall portion at the opening portion of a bagbody is partially released by forming a gap in the mouth portion, andthen the whole of the bag body is opened by blowing compressed air intothe inside of the bag body through the gap in the mouth portion.

The opening process of a bag body may be performed through a pluralityof processes in this way, but may be performed in a single process.Specifically, the process of forming a gap in the mouth portion of a bagbody itself also corresponds to the opening process of a bag body in abroad sense. Therefore, if the mouth portion of a bag body can be openedto a desired state only by the process of forming a gap in the mouthportion of the bag body, other processes (for example, a process ofblowing compressed air into the inside of the bag body) are notnecessarily required to be performed.

The bag opening apparatus described below comprises: a gap formationunit which bends at least the front wall portion, of the front wallportion and the back wall portion constituting the mouth portion of abag body, in such a manner that a gap is formed between the front wallportion and the back wall portion at the mouth portion; and an airblowing unit which blows air toward the gap. Specifically, as typicalexamples of a bag opening apparatus according to the present invention,there are a bag opening apparatus which bends both the front wallportion and the back wall portion of a bag body, and a bag openingapparatus which bends only one of the front wall portion and the backwall portion. In the following first embodiment, a bag opening apparatusthat bends each of the front wall portion and the back wall portion of abag body to form a gap will be exemplified. On the other hand, in thesecond embodiment below, a bag opening apparatus that bends only thefront wall portion, of the front wall portion and the back wall portionof a bag body, to form a gap is exemplified.

First Embodiment

FIG. 1 is a plan view illustrating a schematic configuration of a bagopening apparatus 10 according to a first embodiment.

The mouth portion 101 of a bag body 100 to be supplied to the bagopening apparatus 10 is closed. Specifically, in a state in which boththe side portions (in particular, both the side edge portions) of a bagbody 100 are held by a pair of grippers 110 and the front wall portion102 and the back wall portion 103 of the bag body 100 are in closecontact with each other, the bag body 100 is supplied to the bag openingapparatus 10. In particular, each bag body 100 is transferred togetherwith a pair of grippers 110 along a predetermined track extending in thehorizontal direction (for example, a straight line track, a circletrack, or a track formed by combining a straight line and a curved line)so as to sequentially visit a plurality of stations, and isintermittently stopped at the opening station S1 where the bag openingapparatus 10 is provided. Each bag body 100 is opened by the bag openingapparatus 10 while stopping at the opening station S1. A bag body 100having the mouth portion 101 opened by the bag opening apparatus 10 isintermittently transferred toward the other stations (a contentintroduction station, a sealing station, etc.) provided in thesubsequent stages.

A pair of grippers 110 is provided so as to be movable in a direction ofthe horizontal direction parallel to the extension direction (see thearrow “Y” in FIG. 1) in which a bag body 100 extends. When the bagopening apparatus 10 is brought into contact with a bag body 100 at theopening station S1, the grippers 110 forming a pair are disposed atpositions separated relatively from each other, the bag body 100 isstrained in the Y direction by the pair of grippers 110, and each of thefront wall portion 102 and the back wall portion 103 of the bag body 100is placed in a stretched state without looseness. On the other hand,when the bag opening apparatus 10 bends the front wall portion 102 andthe back wall portion 103 as described later, the grippers 110 forming apair are disposed in positions relatively close to each other, thetension of the bag body 100 in the Y direction is released, and each ofthe front wall portion 102 and the back wall portion 103 of the bag body100 is placed in a slack state.

The gap formation unit 11 of the bag opening apparatus 10 of the presentembodiment includes: a first press drive member 23 (a first movementarm) and a second press drive member 24 (a second movement arm); a firstholding unit 25 and a second holding unit 26 which are attached to thefirst press drive member 23; and a third holding unit 27 and a fourthholding unit 28 which are attached to the second press drive member 24.

A first opening unit 21 includes the first press drive member 23, thefirst holding unit 25 and the second holding unit 26, and moves in anintegrated fashion. Similarly, a second opening unit 22 includes thesecond press drive member 24, the third holding unit 27 and the fourthholding unit 28, and moves in an integrated fashion. A bag body 100gripped by the grippers 110 is disposed between the first opening unit21 and the second opening unit 22, the first opening unit 21 is arrangedon the front surface side of the bag body 100, and the second openingunit 22 is arranged on the back surface side of the bag body 100. Thefirst to the fourth holding units 25 to 28 are disposed above thegrippers 110 in terms of the vertical direction, and when the first tothe fourth holding units 25 to 28 contact the bag body 100, the first tothe fourth holding units 25 to 28 contact the bag body 100 at positionsclose to the mouth portion 101.

Each of the first press drive member 23 and the second press drivemember 24 is provided so as to be driven to be horizontally movable indirections toward and away from each other (see an arrow “X” In FIG. 1)by a drive unit which is not illustrated (such as an air cylinder or amotor), and moves forward and backward relative to the bag body 100.

The first press drive member 23 moves the first holding unit 25 and thesecond holding unit 26 between a position where the first holding unit25 and the second holding unit 26 are distanced from the front wallportion 102 of a bag body 100 and a position where the first holdingunit 25 and the second holding unit 26 are pressed against the frontwall portion 102. The second press drive member 24 moves the thirdholding unit 27 and the fourth holding unit 28 between a position wherethe third holding unit 27 and the fourth holding unit 28 are distancedfrom the back wall portion 103 of a bag body 100 and a position wherethe third holding unit 27 and the fourth holding unit 28 are pressedagainst the back wall portion 103.

The first holding unit 25 and the second holding unit 26 are provided atpositions distanced from each other in the Y direction, and the thirdholding unit 27 and the fourth holding unit 28 are provided at positionsdistanced from each other in the Y direction. The first holding unit 25and the second holding unit 26 are each arranged to protrude from thefirst press drive member 23 toward the bag body 100. The third holdingunit 27 and the fourth holding unit 28 of the second opening unit 22 areeach arranged to protrude from the second press drive member 24 towardthe bag body 100.

For example, when the first press drive member 23 is moved in adirection in which the first press drive member 23 approaches the secondpress drive member 24, the first holding unit 25 and the second holdingunit 26 contact areas of the front wall portion 102 of the bag body 100which are distanced from each other in the Y direction, and the firstholding unit 25 and the second holding unit 26 are pressed against thefront wall portion 102. Similarly, when the second press drive member 24is moved in a direction in which the second press drive member 24approaches the first press drive member 23, the third holding unit 27and the fourth holding unit 28 contact areas of the back wall portion103 of the bag body 100 which are distanced from each other in the Ydirection, and the third holding unit 27 and the fourth holding unit 28are pressed against the back wall portion 103.

Each of the first holding unit 25, the second holding unit 26, the thirdholding unit 27, and the fourth holding unit 28 includes a contact part31, a support part 32 that swingably supports the contact part 31, andan urging part 33 which urges the contact part 31 via the support part32.

The contact parts 31 of the first holding unit 25 and the second holdingunit 26 are regions which directly contact the front wall portion 102when the first press drive member 23 presses the first holding unit 25and the second holding unit 26 against the front wall portion 102.Further, the contact parts 31 of the third holding unit 27 and thefourth holding unit 28 are regions which directly contact the back wallportion 103 when the second press drive member 24 presses the thirdholding unit 27 and the fourth holding unit 28 against the back wallportion 103. The contact parts 31 of the present embodiment include anelastic member (second elastic member). Although the elastic member ofthe contact parts 31 is not limited, the elastic member of the contactparts 31 is preferably a member having a high friction coefficient andexcellent adhesion, and typically silicone or urethane may be used asthe elastic member of the contact parts 31. As will be described later,in the bag opening apparatus 10 of the present embodiment, the contactparts 31 of the first holding unit 25 to the fourth holding unit 28displace the bag surfaces of a bag body 100 (that is, the front wallportion 102 and the back wall portion 103) from each other due to thefriction force so as to form a gap in the mouth portion 101 of the bagbody 100. Therefore, by configuring the contact parts 31 of the firstholding unit 25 to the fourth holding unit 28 with an elastic member asdescribed above, the grip force of the contact parts 31 is secured andthereby the opening process of a bag body 100 is stabilized, andfurther, it is possible to make a bag body 100 less likely to be damagedby the contact parts 31.

In the illustrated first holding unit 25, a link mechanism isconstituted by a first link 34, a second link 35, and the support part32. The first link 34 is fixedly attached to the first press drivemember 23, protrudes from the first press drive member 23 toward a bagbody 100 (specifically, in the horizontal direction (that is, the Xdirection) perpendicular to the Y direction), and supports one side ofthe support part 32 via a second support shaft 42 in a swingable manner.A distal end portion on one side of the second link 35 swingablysupports the other side of the support part 32 via a first support shaft41. The other side of the second link 35 is swingably attached to thefirst press drive member 23 via a third support shaft 43 (a fasteningpart), and is provided to be movable back and forth in a directiontoward the bag body 100 and in a direction away from the bag body 100.

The illustrated second link 35 has a reduced diameter portion 36 havinga small diameter in part between the third support shaft 43 and aconnecting portion between the second link 35 and the support part 32 ofthe first holding unit 25. An urging part 33 constituted by a compressedspring is disposed in this reduced diameter portion 36. The urging part33 of the first holding unit 25 urges the support part 32 and the secondlink 35 of the first holding unit 25 toward the connection portionbetween the second link 35 and the support part 32 of the first holdingunit. Specifically, the urging part 33 of the first holding unit 25urges the contact part 31 of the first holding unit 25, via the supportpart 32 and the second link 35 of the first holding unit 25, in adirection including a component of the direction opposing a direction inwhich the contact part 31 of the first holding unit 25 swings when thefirst press drive member 23 presses the first holding unit 25 againstthe front wall portion 102. In particular, the urging part 33 of thefirst holding unit 25 of the present embodiment is combined with theabove-described link mechanism to urge the second link 35 and thesupport part 32 in such a manner that the contact part 31 of the firstholding unit 25 is distanced from the contact part 31 of the secondholding unit 26.

The support part 32 of the first holding unit 25 is disposed in aposture tilted with respect to the movement direction (that is, the Xdirection) of the first opening unit 21 and the second opening unit 22.In particular, the tip of the support part 32 of the first holding unit25 on the side where the contact part 31 is disposed (specifically, thetip relatively close to the bag body 100) is arranged closer to thesecond holding unit 26 in the Y direction than the opposite tip(specifically, the tip relatively farther from the bag body 100). Thus,when the first holding unit 25 (in particular, the contact part 31) Ispressed against the bag body 100, the support part 32 and the contactpart 31 of the first holding unit 25 swing so as to approach the supportpart 32 and the contact part 31 of the second holding unit 26.

The second holding unit 26 has a configuration similar to theabove-described first holding unit 25. Specifically, the second holdingunit 26 includes a first link 34, a second link 35, a reduced diameterportion 36, a first support shaft 41, a second support shaft 42 and athird support shaft 43 in addition to the contact part 31, the supportpart 32 and the urging part 33. However, the urging part 33 of thesecond holding unit 26 is combined with the link mechanism constitutedby the support part 32, the first link 34 and the second link 35 of thesecond holding unit 26 to urge the second link 35 and the support part32 in such a manner that the contact part 31 of the second holding unit26 is distanced from the contact part 31 of the first holding unit 25.Specifically, the urging part 33 of the second holding unit 26 urges thecontact part 31 of the second holding unit 26, via the support part 32and the second link 35 of the second holding unit 26, in a directionincluding a component of the direction opposing a direction in which thecontact part 31 of the second holding unit 26 swings when the firstpress drive member 23 presses the second holding unit 26 against thefront wall portion 102.

The third holding unit 27 and the fourth holding unit 28 attached to thesecond press drive member 24 have configurations similar to the firstholding unit 25 and the second holding unit 26 attached to the firstpress drive member 23, and each Include a contact part 31, a supportpart 32, an urging part 33, a first link 34, a second link 35, a reduceddiameter portion 36, a first support shaft 41, a second support shaft42, and a third support shaft 43.

In each of the third holding unit 27 and the fourth holding unit 28, thefirst link 34 is fixedly attached to the second press drive member 24,protrudes from the second press drive member 24 towards the bag body 100in the X direction, and supports one side of the support part 32 via thesecond support shaft 42 in a swingable manner. Further, the second link35 of each of the third holding unit 27 and the fourth holding unit 28is swingably attached to the second press drive member 24 via the thirdsupport shaft 43 (a fastening part), is provided to be movable back andforth in a direction towards the bag body 100 and in a direction awayfrom the bag body 100, and supports the other side of the support part32 via the first support shaft 41 in a swingable manner.

The urging part 33 of the third holding unit 27 is combined with thelink mechanism constituted by the support part 32, the first link 34 andthe second link 35 of the third holding unit 27 to urge the second link35 and the support part 32 in such a manner that the contact part 31 ofthe third holding unit 27 is distanced from the contact part 31 of thefourth holding unit 28. Further, the urging part 33 of the fourthholding unit 28 is combined with the link mechanism constituted by thesupport part 32, the first link 34 and the second link 35 of the fourthholding unit 28 to urge the second link 35 and the support part 32 insuch a manner that the contact part 31 of the fourth holding unit 28 isdistanced from the contact part 31 of the third holding unit 27.

As described above, when the first press drive member 23 presses thefirst holding unit 25 and the second holding unit 26 against the frontwall portion 102, the support part 32 and the contact part 31 of thefirst holding unit 25 swing against the urging force of the urging part33 of the first holding unit 25 in such a manner that the contact part31 of the first holding unit 25 approaches the contact part 31 of thesecond holding unit 26. Specifically, when the first press drive member23 presses the first holding unit 25 against the front wall portion 102,the contact part 31 of the first holding unit 25 swings against theurging force of the urging part 33 of the first holding unit 25 whilecontacting the front wall portion 102 and thereby bends the front wallportion 102. In addition, when the first press drive member 23 pressesthe first holding unit 25 and the second holding unit 26 against thefront wall portion 102, the support part 32 and the contact part 31 ofthe second holding unit 26 swing against the urging force of the urgingpart 33 of the second holding unit 26 in such a manner that the contactpart 31 of the second holding unit 26 approaches the contact part 31 ofthe first holding unit 25. In this way, when the first press drivemember 23 presses the second holding unit 26 against the front wallportion 102, the contact part 31 of the second holding unit 26 swingsagainst the urging force of the urging part 33 of the second holdingunit 26 and thereby bends the front wall portion 102. As describedabove, when the first press drive member 23 presses the first holdingunit 25 and the second holding unit 26 against the front wall portion102, at least one of the contact part 31 of the first holding unit 25and the contact part 31 of the second holding unit 26 is swung in such amanner that the distance between the contact part 31 of the firstholding unit 25 and the contact part 31 of the second holding unit 26 ismade smaller, and thereby the front wall portion 102 is bent and a gapcan be created in the mouth portion 101.

In particular, in the present embodiment, in a situation where thecontact part 31 of the first holding unit 25 and the contact part 31 ofthe third holding unit 27 are opposed to each other via the front wallportion 102 and the back wall portion 103 of the bag body 100 while thecontact part 31 of the second holding unit 26 and the contact part 31 ofthe fourth holding unit 28 are opposed to each other via the front wallportion 102 and the back wall portion 103 of the bag body 100, the firstpress drive member 23 presses the first holding unit 25 and the secondholding unit 26 against the front wall portion 102, and the second pressdrive member 24 presses the third holding unit 27 and the fourth holdingunit 28 against the back wall portion 103. Thus, the first holding unit25 (for example, the contact part 31, the support part 32 and the secondlink 35) and the third holding unit 27 (for example, the contact part31, the support part 32 and the second link 35) behave in a symmetricfashion with respect to the bag body 100, and the second holding unit 26and the fourth holding unit 28 also behave in a symmetric fashion withrespect to the bag body 100.

Meanwhile, the air blowing unit 12 is installed above the mouth portion101 of a bag body 100 with respect to the vertical direction, and theejection port 45 of the air blowing unit 12 is directed towards themouth portion 101 of the bag body 100. The air blowing unit 12 isconnected to an air supply source (not shown), and compresses the airfrom the air supply source and ejects the compressed air from theejection port 45. Although the illustrated air blowing unit 12 has theejection port 45 in the form of a nozzle, the air blowing unit 12 andthe ejection port 45 may take any form capable of appropriately ejectingcompressed air.

Typically, the ejection port 45 of the air blowing unit 12 is disposedabove the center position of the mouth portion 101 of a bag body 100;however, the relative arrangement position and direction of the ejectionport 45 with respect to the mouth portion 101 of a bag body 100 are notlimited. For example, the ejection port 45 of the air blowing unit 12may be oriented so as to eject compressed air in an oblique directionwith respect to the mouth portion 101 of a bag body 100. Further, theejection port 45 of the air blowing unit 12 may be oriented so as toeject compressed air toward a position of the mouth portion 101 of a bagbody 100 other than the center position.

Next, a bag opening method according to which a gap is formed betweenthe front wall portion 102 and the back wall portion 103 of a bag body100 and the bag body 100 is opened will be described.

A bag opening method performed by using the above-described bag openingapparatus 10 includes: a step of bending both the front wall portion 102and the back wall portion 103 to form a gap between the front wallportion 102 and the back wall portion 103; and a step of blowingcompressed air from the air blowing unit 12 into the gap formed in thebag mouth to spread the inside of the bag body 100 with the compressedair.

FIGS. 2 to 4 are process diagrams of a bag opening method according tothe first embodiment.

First, as shown in FIG. 2, the first opening unit 21 (the first pressdrive member 23, the first holding unit 25 and the second holding unit26) and the second opening unit 22 (the second press drive member 24,the third holding unit 27 and the fourth holding unit 28) are arrangedat positions separated from a bag body 100 gripped by a pair of grippers110.

Then, as shown in FIG. 3, the first opening unit 21 and the secondopening unit 22 are moved to approach each other in such a manner thatthe contact parts 31 of the first holding unit 25 to the fourth holdingunit 28 are brought into contact with the bag body 100. As a result, thecontact part 31 of the first holding unit 25 and the contact part 31 ofthe third holding unit 27 are opposed to each other with the bag body100 interposed therebetween, and the contact part 31 of the secondholding unit 26 and the contact part 31 of the fourth holding unit 28are opposed to each other with the bag body 100 interposed therebetween.

The contact timing of the first holding unit 25 to the fourth holdingunit 28 with respect to the bag body 100 is not limited. All of thefirst holding unit 25 to the fourth holding unit 28 may be brought intocontact with the bag body 100 at almost the same time, or one of the setof the first holding unit 25 and the second holding unit 26 (that is,the first opening unit 21) and the set of the third holding unit 27 andthe fourth holding unit 28 (that is, the second opening unit 22) maycome into contact with the bag body 100 prior to the other.

Then, as shown in FIG. 4, both the first opening unit 21 and the secondopening unit 22 are further moved toward the bag body 100, so that thefront wall portion 102 and the back wall portion 103 of the bag body 100are bent. Specifically, the first press drive member 23 presses thefirst holding unit 25 and the second holding unit 26 against the frontwall portion 102 to force the support part 32 of the first holding unit25 to swing against the urging force of the urging part 33 of the firstholding unit 25 and to force the support part 32 of the second holdingunit 26 to swing against the urging force of the urging part 33 of thesecond holding unit 26 in such a manner that the contact part 31 of thefirst holding unit 25 and the contact part 31 of the second holding unit26 approach each other. Similarly, the second press drive member 24presses the third holding unit 27 and the fourth holding unit 28 againstthe back wall portion 103 to force the support part 32 of the thirdholding unit 27 to swing against the urging force of the urging part 33of the third holding unit 27 and to force the support part 32 of thefourth holding unit 28 to swing against the urging force of the urgingpart 33 of the fourth holding unit 28 in such a manner that the contactpart 31 of the third holding unit 27 and the contact part 31 of thefourth holding unit 28 approach each other.

In this way, the contact parts 31 of the first holding unit 25 to thefourth holding unit 28 are moved inward in the width direction of thebag body 100 in a state of contacting the bag surfaces of the bag body100, so that the front wall portion 102 and the back wall portion 103 ofthe bag body 100 are displaced inward in the width direction. As aresult, a gap is formed in the mouth portion 101 and the bag body 100 isopened. In this situation, the grippers 110 forming a pair are moved toapproach each other while the grippers 110 grip both side portions(particularly both side edge portions) of the bag body 100, so that thefront wall portion 102 and the back wall portion 103 are loosened to theextent that a gap can be formed in the mouth portion 101. It ispreferable that this approaching movement of the pair of grippers 110 becarried out after the contact parts 31 of the first holding unit 25 tothe fourth holding unit 28 have contacted the bag body 100 (see FIG. 3).Further, it is preferable that the approaching movement of the pair ofgrippers 110 be carried out before the contact part 31 of the firstholding unit 25 and the contact part 31 of the second holding unit 26come close to each other and before the contact part 31 of the thirdholding unit 27 and the contact part 31 of fourth holding unit 28 comeclose to each other. Alternatively, it is preferable that theapproaching movement of the pair of grippers 110 be carried outsimultaneously with the time when the contact part 31 of the firstholding unit 25 and the contact part 31 of the second holding unit 26come close to each other and simultaneously with the contact part 31 ofthe third holding unit 27 and the contact part 31 of fourth holding unit28 come close to each other.

As described above, before or during swinging of the contact part 31 ofthe first holding unit 25 by the first press drive member 23 pressingthe first holding unit 25 against the front wall portion 102, at leastone of the grippers 110 forming a pair (both the grippers 110 in thepresent embodiment) is moved in such a manner that the distance betweenthe grippers 110 forming a pair becomes smaller.

Then, compressed air is blown from the air blowing unit 12 (see FIG. 1)toward the gap in the mouth portion 101 of the bag body 100, althoughthe illustration in the drawings is omitted. As a result, the compressedair is supplied to the interior of the bag body 100, which enables theinside of the bag body 100 to spread up to the bag bottom.

As described above, according to the bag opening apparatus 10 and thebag opening method of the present embodiment, negative pressure suctionusing a suction cup or the like is not used in the opening process of abag body 100. Thus, the period of time for forming a negative pressureis not required, the period of time for the opening process can beshortened, and the processing can be performed at high speed.

In general, a bag opening method using suction cups requires: (1) a stepof pressing the suction cups against the front surface and the backsurface of a bag body respectively; (2) a step of performing deairingand forming a negative pressure between each suction cup and the bagsurface; (3) a step of measuring the pressure between the suction cupand the bag surface after elapse of a predetermined time from the startof the deairing; (4) a step of distancing the suction cups from eachother to form a gap in the mouth portion; and (5) a step of blowingcompressed air toward the gap. In particular, the above-mentioned “(2) astep for forming a negative pressure” requires a decent period of time,and if a decent time is not secured for “(2) a step for forming anegative pressure”, it is not possible for each suction cup toadequately suck the bag surface and thus the bag body cannot be properlyopened.

In contrast, the bag opening method according to the present embodimentincludes: (a) a step of bringing the first holding unit 25 to the fourthholding unit 28 into contact with a bag body 100; (b) a step of pressingthe first holding unit 25 to the fourth holding unit 28 against the bagbody 100 to form a gap in the mouth portion 101; and (c) a step ofblowing compressed air into the gap. As described above, according tothe above-described embodiment, a step itself of forming a negativepressure is unnecessary, and a gap can be appropriately created in themouth portion 101 of a bag body 100 by just the actions of pressing thefirst holding unit 25 to the fourth holding unit 28 against a bag body100.

In particular, by moving a pair of holding units (that is, “a set of thefirst holding unit 25 and the second holding unit 26” or “a set of thethird holding unit 27 and the fourth holding unit 28”) toward a bag body100, it is possible not only to bring the contact parts 31 of the pairof holding units into contact with the bag body 100 but also to move thepair of contact parts 31 inward in the width direction of the bag body100. Specifically, the first holding unit 25 to the fourth holding unit28 of the present embodiment can be moved inward in the width directionalmost simultaneously with the contact with a bag body 100 so that thefront wall portion 102 and the back wall portion 103 of the bag body 100are bent. As described above, “(a) the step of bringing the firstholding unit 25 to the fourth holding unit 28 into contact with a bagbody 100” and “(b) a step of forming a gap in the mouth portion 101” canbe performed in a sequential processing in which the first opening unit21 and the second opening unit 22 are moved toward a bag body 100, andtherefore it is possible to form a gap in the mouth portion 101 veryefficiently in a short time.

By forming a gap in the mouth portion 101 of a bag body 100 in a shorttime in this way, “(c) a step of blowing compressed air into the gap”performed subsequently can be expedited. As a result, it is possible toallocate a sufficient time to “(c) a step of blowing compressed air intothe gap” and thereby open a bag body 100 more reliably with compressedair. Further, it is also possible to shorten the period of time requiredfor the entire opening process including the above (a) to (c) steps.

Incidentally, when the inventors measured the period of time requiredfor the above-described series of steps (that is, the above-mentioned(a) to (c) steps) using the bag opening apparatus 10 according to theabove-described first embodiment, it took approximately 0.15 seconds forone bag body 100. In contrast, when the inventors measured the period oftime required for the above-described series of steps (that is, theabove-mentioned (1) to (5) steps) using a conventional apparatus withsuction cups, it took approximately 0.5 seconds for one bag body 100. Asdescribed above, according to the bag opening apparatus 10 of thepresent embodiment, it is possible to perform the opening process of abag body 100 at least approximately three times faster than theconventional apparatus.

Further, in the bag opening apparatus 10 of the present embodiment, anegative pressure forming means, such as a vacuum pump, is unnecessary,and there is no need to control such a negative pressure forming means.In particular, in a conventional apparatus using suction cups, a commonnegative pressure forming means, such as a pump, is typically connectedto a plurality of suction cups in many cases, and in such a conventionalapparatus, there is concern that a problem occurring in one suction cupmay affect another suction cup. In contrast, in the bag openingapparatus 10 of the present embodiment, there is no concern of suchpropagation of problem.

In the present embodiment, the opening process of a bag body 100 isperformed by combining a step of moving the first opening unit 21 (inparticular, the first press drive member 23) and the second opening unit22 (in particular, the second press drive member 24), a step of movingthe pair of grippers 110, and a step of blowing air from the air blowingunit 12. The driving of these elements may be controlled by a controlunit (not shown) according to the driving state of one another, or maybe performed based on predetermined timing. For example, the controlunit may monitor the movement amounts and the arrangement positions ofthe first press drive member 23 and the second press drive member 24,and may move the grippers 110 or may cause the air blowing unit 12 toeject compressed air according to these movement amounts and arrangementpositions. Further, the time when the movement of the first press drivemember 23 and the second press drive member 24 is performed, the timewhen the movement of the grippers 110 is performed, and the time whenthe air ejection of the air blowing unit 12 is performed, may bedetermined in advance within the time period when a bag body 100 isintermittently stopped and stays at the opening station S1. Further, themovement of the first press drive member 23 and the second press drivemember 24, the movement of the grippers 110, and the air ejection of theair blowing unit 12 may be performed by combining the control based onthe drive states and the driving based on the time determined inadvance.

Second Embodiment

In a bag opening apparatus 10 of the present embodiment, elements whichare the same as or similar to those of the above-described bag openingapparatus 10 of the first embodiment are denoted by the same referencenumerals, and the detailed description thereof will be omitted.

FIG. 5 is a plan view illustrating an example of a state of a bag body100 which may occur in the apparatus and the method according to thefirst embodiment. According to the bag opening apparatus 10 and the bagopening method according to the above-described first embodiment, whenthe front wall portion 102 and the back wall portion 103 of a bag body100 bend in mutually different directions in terms of the X direction asshown in FIG. 4, a desired gap can be formed in the mouth portion 101 ofthe bag body 100. On the other hand, when the front wall portion 102 andthe back wall portion 103 of a bag body 100 bend in the same directionwith respect to the X direction as shown in FIG. 5, a desired gap is notformed in the mouth portion 101 of the bag body 100.

A bag opening apparatus 10 and a bag opening method according to thepresent embodiment can effectively avoid the trouble shown in FIG. 5,and can form a gap between the front wall portion 102 and the back wallportion 103 more reliably so that the bag body 100 can be properlyopened.

FIG. 6 is a plan view Illustrating a schematic configuration of a bagopening apparatus 10 according to the second embodiment.

In the bag opening apparatus 10 according to the present embodiment, thefirst opening unit 21 has almost the same configuration as that of theabove-described first embodiment, but the second opening unit 22 has areceiving part 50 instead of the third holding unit 27 and the fourthholding unit 28. Specifically, the gap formation unit 11 according tothe present embodiment includes a receiving part 50 (i.e., a receivingplate in the Illustrated example) disposed on the back wall portion 103side, and the receiving part 50 has a receiving surface 51. Thereceiving surface 51 extends in parallel with the extension direction(that is, the Y direction) of the back wall portion 103 of a bag body100 gripped by a pair of grippers 110, and is disposed above thegrippers 110 with respect to the vertical direction. The receiving part50 includes an elastic member 52 (first elastic member) that forms thereceiving surface 51, and the elastic member 52 is typically silicone orurethane.

The second press drive member 24 to which the receiving part 50 isattached can be moved in the same manner as in the above-described firstembodiment, and can advance and retreat the receiving surface 51 of thereceiving part 50 with respect to the bag body 100 (in particular, theback wall portion 103). While the second press drive member 24 of thepresent embodiment brings the receiving surface 51 of the receiving part50 into contact with the back wall portion 103 of the bag body 100, thesecond press drive member 24 basically does not press the receiving part50 (receiving surface 51) against the back wall portion 103. Thereceiving surface 51 of the receiving part 50 acts as a pressing surfacefor the first holding unit 25 and the second holding unit 26 when thefirst holding unit 25 and the second holding unit 26 are caused to beswung. When the first holding unit 25 and the second holding unit 26 arepressed against the front wall portion 102 of a bag body 100, thereceiving surface 51 is fixedly arranged, and pushes back the firstholding unit 25 and the second holding unit 26 while supporting the backwall portion 103. As a result, when the first holding unit 25 and thesecond holding unit 26 are pressed against the front wall portion 102 ofa bag body 100, the back wall portion 103 of the bag body 100 is held onthe receiving surface 51 and basically keeps its almost planar state atthe same position, and only the front wall portion 102 is bent by thefirst holding unit 25 and the second holding unit 26. However, thesecond press drive member 24 may press the receiving part 50 (receivingsurface 51) against the back wall portion 103. In this case, the backwall portion 103 may be tensioned by the force received from thereceiving surface 51 of the receiving part 50 while an excessive load isnot applied to the bag body 100 (in particular, the back wall portion103) from the receiving surface 51 of the receiving part 50 and the flatstate of the back wall portion 103 along the receiving surface 51 ismaintained.

The other configuration is almost the same as that of theabove-described first embodiment.

The bag opening method using the bag opening apparatus 10 of the presentembodiment described above includes: a step of bending the front wallportion 102 of a bag body 100 to form a gap between the front wallportion 102 and the back wall portion 103; and a step of blowingcompressed air from the air blowing unit 12 toward the gap formed in thebag mouth to spread the interior of the bag body 100 with the compressedair. The back wall portion 103 of the bag body 100 is supported by thereceiving surface 51 of the receiving part 50 and basically maintains astate of extending linearly in the Y direction.

FIGS. 7 to 9 are process diagrams of a bag opening method according tothe second embodiment, showing states in which the bag opening apparatusis viewed from above. FIGS. 10 to 13 are process diagrams of the bagopening method according to the second embodiment, showing states inwhich the bag opening apparatus is viewed from the side. In FIGS. 10 to13, the arrow marked with “Z” corresponds to the vertical direction.

First, as shown in FIGS. 7 and 10, the first opening unit 21 (the firstpress drive member 23, the first holding unit 25 and the second holdingunit 26) and the second opening unit 22 (the second press drive member24 and the receiving part 50) are arranged at positions separated from abag body 100 gripped by a pair of grippers 110 in the horizontaldirection (in particular, the X direction).

Then, as shown in FIGS. 8 and 11, the first opening unit 21 and thesecond opening unit 22 are moved to approach each other in such a mannerthat the first holding unit 25 and the second holding unit 26 arebrought into contact with the front wall portion 102 of the bag body 100and the receiving surface 51 of the receiving part 50 is brought intocontact with the back wall portion 103 of the bag body 100. As a result,the first holding unit 25 and the second holding unit 26 are opposed tothe receiving surface 51 of the receiving part 50 via the bag body 100.

The contact timing of the first holding unit 25, the second holding unit26 and the receiving surface 51 of the receiving part 50 with respect tothe bag body 100 is not limited. All of the first holding unit 25, thesecond holding unit 26 and the receiving part 50 may be brought intocontact with the bag body 100 at almost the same time, or one of thereceiving part 50 (that is, the second opening unit 22) and a set of thefirst holding unit 25 and the second holding unit 26 (that is, the firstopening unit 21) may come into contact with the bag body 100 prior tothe other. For example, by bringing the receiving part 50 into contactwith the bag body 100 (specifically, the back wall portion 103) prior tothe first holding unit 25 and the second holding unit 26, the firstholding unit 25 and the second holding unit 26 can subsequently performthe contact operation and the pressing operation with respect to the bagbody 100 (specifically, the front wall portion 102) in a continuousmanner without stopping.

Then, as shown in FIGS. 9 and 12, the first opening unit 21 is furthermoved toward the bag body 100 so that the front wall portion 102 of thebag body 100 is bent. Specifically, the first holding unit 25 and thesecond holding unit 26 are pressed against the front wall portion 102 bythe first press drive member 23, and thereby the support part 32 of thefirst holding unit 25 is swung against the urging force of the urgingpart 33 of the first holding unit 25 and the support part 32 of thesecond holding unit 26 is swung against the urging force of the urgingpart 33 of the second holding unit 26 so that the contact part 31 of thefirst holding unit 25 and the contact part 31 of the second holding unit26 approach each other.

On the other hand, while the contact part 31 of the first holding unit25 and the contact part 31 of the second holding unit 26 approach eachother, the receiving part 50 is stopped in a state of being in contactwith the back wall portion 103 of the bag body 100, and the back wallportion 103 is supported on the receiving surface 51 of the receivingpart 50 and is kept almost parallel to the Y direction.

As described above, in a state where the front wall portion 102 and theback wall portion 103 are sandwiched between the receiving surface 51and each of the first holding unit 25 and the second holding unit 26,the first press drive member 23 further presses the first holding unit25 and the second holding unit 26 against the front wall portion 102. Asa result, the first holding unit 25 and the second holding unit 26 moveinward in the width direction of the bag body 100 while being pressedagainst the front wall portion 102 of the bag body 100. In this way, bymoving the contact part 31 of the first holding unit 25 and the contactpart 31 of the second holding unit 26 placed in contact with the frontwall portion 102 inward in the width direction of the bag body 100, thefront wall portion 102 of the bag body 100 is displaced inward in thewidth direction. As a result, a gap is formed in the mouth portion 101of the bag body 100.

Then, as shown in FIG. 13, compressed air is blown from the air blowingunit 12 toward the gap in the mouth portion 101 of the bag body 100. Asa result, the compressed air enters into the bag body 100, enabling theinside of the bag body 100 to spread to the bag bottom.

As described above, according to the bag opening apparatus 10 and thebag opening method of the present embodiment, a bag body 100 can beopened. In particular, since the opening process of a bag body 100 isperformed in a state where the back wall portion 103 of the bag body 100is supported by the receiving part 50, the problem that the front wallportion 102 and the back wall portion 103 of the bag body 100 are bentin the same direction as each other (see FIG. 5) can be effectivelyavoided.

MODIFIED EXAMPLES

The present invention is not limited to the above-described embodimentsand modified examples. For example, various modifications may be made toeach element of the embodiments and the modified examples describedabove.

First Modified Example

FIG. 14 is a plan view illustrating a schematic configuration of a bagopening apparatus 10 according to a first modified example.

In the first holding unit 25 to the fourth holding unit 28 of theabove-described embodiments, the first link 34 is fixedly provided withrespect to the first press drive member 23 or the second press drivemember 24; however, the first link 34 may be provided so as to becapable of swinging with respect to the first press drive member 23 orthe second press drive member 24.

The first links 34 of the first holding unit 25 and the second holdingunit 26 according to the present modified example shown in FIG. 14 eachhave an end on one side connected swingably to the first press drivemember 23 via the third support shaft 43, and each have an end on theother side connected swingably to one side of the support part 32 viathe second support shaft 42. The other configuration is almost the sameas that of the bag opening apparatus 10 of the above-described secondembodiment.

In this modified example, the first link 34, the second link 35 and thesupport part 32 of each of the first holding unit 25 and the secondholding unit 26 constitute a link mechanism. The urging part 33 of thefirst holding unit 25 is combined with this link mechanism to urge thesupport part 32 and the second link 35 of the first holding unit 25 insuch a manner that the contact part 31 of the first holding unit 25 isdistanced from the contact part 31 of the second holding unit 26.Further, the urging part 33 of the second holding unit 26 is combinedwith this link mechanism to urge the support part 32 and the second link35 of the second holding unit 26 in such a manner that the contact part31 of the second holding unit 26 is distanced from the contact part 31of the first holding unit 25. Thus, by causing the first press drivemember 23 to press the contact part 31 of the first holding unit 25 andthe contact part 31 of the second holding unit 26 against the front wallportion 102 of a bag body in a state in which the back wall portion 103of the bag body 100 is supported by the receiving surface 51 of thereceiving part 50, the front wall portion 102 can be bent to form a gapin the mouth portion 101.

While FIG. 14 shows an example in which a first link 34 providedswingably is applied to the above-described second embodiment, thisfirst link 34 may be applied to the above-described first embodiment.Specifically, not only in the first holding unit 25 and the secondholding unit 26 but also in the third holding unit 27 and the fourthholding unit 28, the end of one side of a first link 34 may be swingablyattached to the second press drive member 24 via the third support shaft43, and the end of the other side of the first link 34 is swingablyattached to one side of the support part 32 via the second support shaft42.

Other Modified Examples

For example, the bag opening apparatus 10 may supplementarily utilize asuction cup. As a specific example, a suction cup is provided betweenthe first holding unit 25 and the second holding unit 26, and when thefront wall portion 102 of a bag body 100 is bent by the first holdingunit 25 and the second holding unit 26, the front wall portion 102 maybe sucked by the suction cup. In this case, by moving the suction cup,the front wall portion 102 can be moved to open the bag body 100. Inthis way, it is possible to open a bag body 100 without blowing air intothe mouth portion 101 of the bag body 100, and therefore, theabove-described air blowing unit 12 may not be provided.

Further, in the embodiments and the modified examples described above,when the first holding unit 25 and the second holding unit 26 arepressed against the front wall portion 102 of a bag body 100, both thecontact part 31 of the first holding unit 25 and the contact part 31 ofthe second holding unit 26 are moved in the Y direction (that is, theextension direction of the bag body 100); however, only one of thecontact parts 31 of the first holding unit 25 and the second holdingunit 26 may be moved in the Y direction. Similarly, when the thirdholding unit 27 and the fourth holding unit 28 are pressed against theback wall portion 103 of a bag body 100, only one of the contact parts31 of the third holding unit 27 and the fourth holding unit 28 may bemoved in the Y direction.

Further, in the bag opening apparatus 10 of the second embodiment shownin FIGS. 6 to 13, the receiving surface 51 of the receiving part 50 mayhave any structure capable of appropriately supporting the back wallportion 103 of a bag body 100. For example, one or more of suction holesmay be formed in the receiving surface 51, and in a state in which theback wall portion 103 of a bag body 100 is in contact with the receivingsurface 51 of the receiving part 50, the suction may be performedthrough the one or more of suction holes. In this case, the back wallportion 103 of a bag body 100 can be sucked by the receiving part 50,and the back wall portion 103 can be effectively prevented fromdeflecting when the front wall portion 102 of the bag body 100 is bentby the first holding unit 25 and the second holding unit 26.

Further, in the above-described embodiments and modified examples, acase where a bag body 100 is intermittently transferred with grippers110 and the bag body 100 is opened by the bag opening apparatus 10 whilethe bag body 100 is stopped is described, but the bag opening apparatus10 may open a bag body 100 which is in a moving state. For example, byconfiguring the bag opening apparatus 10 to be movable and by providingthe bag opening apparatus 10 so as to follow a moving bag body 100 in apart of the transfer path of the bag body 100, it is possible for thebag opening apparatus 10 to open the bag body 100 without stopping thebag body 100. Therefore, bag opening apparatuses and bag opening methodsaccording to the present invention can be applied not only toapparatuses adopting an intermittent transport system as described abovebut also to apparatuses which continuously transport a bag body 100without Intermittently stopping the bag body 100. Further, it ispossible that, in an intermittent transfer type apparatus, a bag body100 is opened by the bag opening apparatus 10 while the bag body 100 isintermittently moving.

The embodiments of the present invention include embodiments which eachinclude a constituent element and/or a method other than theabove-described constituent elements and/or methods. Also, embodimentsin which some of the above-described constituent elements and/or methodsare not included may also be Included in the embodiments of the presentinvention. Further, embodiments which each include some constituentelements and/or methods included in a certain embodiment of the presentinvention and some constituent elements and/or methods included inanother embodiment of the present invention may also be included in theembodiments of the present invention. Therefore, constituent elementsand/or methods included in the embodiments and modified examplesdescribed above and embodiments of the present invention which are notdescribed above may be combined with one another, and an embodimentbased on such combination may also be Included in the embodiments of thepresent invention. Further, the effects brought about by the presentinvention are not limited to the above-described effects, and particulareffects depending on the specific configuration of each embodiment canbe exerted. As described above, various additions, modifications andpartial deletions may be made to each element described in the claims,the description, the abstract and the drawings without departing fromthe technical idea and gist of the present invention.

1. A bag opening apparatus comprising a gap formation unit which bends at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap between the front wall portion and the back wall portion, wherein: the gap formation unit includes a first holding unit and a first press drive member which moves the first holding unit between a position where the first holding unit is separated from the front wall portion and a position where the first holding unit is pressed against the front wall portion, the first holding unit includes a contact part, a support part which swingably supports the contact part, and an urging part which urges the contact part via the support part, and when the first press drive member presses the first holding unit against the front wall portion, the contact part is swung against urging force of the urging part while the contact part is in contact with the front wall portion so as to bend the front wall portion.
 2. The bag opening apparatus as defined in claim 1, wherein: the gap formation unit further includes a second holding unit, the first press drive member moves not only the first holding unit but also the second holding unit between the position where the first holding unit and the second holding unit are separated from the front wall portion and the position where the first holding unit and the second holding unit are pressed against the front wall portion, and when the first press drive member presses the first holding unit and the second holding unit against the front wall portion, the contact part of the first holding unit is swung so as to approach the second holding unit while the contact part of the first holding unit is in contact with the front wall portion.
 3. The bag opening apparatus as defined in claim 2, wherein: the second holding unit includes a contact part, a support part which swingably supports this contact part, and an urging part which urges this contact part via the support part, and when the first press drive member presses the first holding unit and the second holding unit against the front wall portion, the contact part of the second holding unit Is swung against urging force of the urging part of the second holding unit so as to approach the contact part of the first holding unit while the contact part of the second holding unit is in contact with the front wall portion.
 4. The bag opening apparatus as defined in claim 1, further comprising an air blowing unit which ejects air toward the gap.
 5. The bag opening apparatus as defined in claim 2, further comprising an air blowing unit which ejects air toward the gap.
 6. The bag opening apparatus as defined in claim 3, further comprising an air blowing unit which ejects air toward the gap.
 7. The bag opening apparatus as defined in claim 3, wherein: the gap formation unit further includes: a third holding unit and a fourth holding unit; and a second press drive member which moves the third holding unit and the fourth holding unit between a position where the third holding unit and the fourth holding unit are separated from the back wall portion and a position where the third holding unit and the fourth holding unit are pressed against the back wall portion, and in a state where the contact part of the first holding unit and a contact part of the third holding unit are opposed to each other via the front and back wall portions and the contact part of the second holding unit and a contact part of the fourth holding unit are opposed to each other via the front and back wall portions, the first press drive member presses the first holding unit and the second holding unit against the front wall portion, and the second press drive member presses the third holding unit and the fourth holding unit against the back wall portion.
 8. The bag opening apparatus as defined in claim 1, wherein: the gap formation unit further includes a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion, and the first press drive member presses the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.
 9. The bag opening apparatus as defined in claim 2, wherein: the gap formation unit further Includes a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion, and the first press drive member presses the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.
 10. The bag opening apparatus as defined in claim 3, wherein: the gap formation unit further includes a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion, and the first press drive member presses the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.
 11. The bag opening apparatus as defined in claim 8, wherein the receiving part includes a first elastic member forming the receiving surface.
 12. The bag opening apparatus as defined in claim 9, wherein the receiving part includes a first elastic member forming the receiving surface.
 13. The bag opening apparatus as defined in claim 10, wherein the receiving part includes a first elastic member forming the receiving surface.
 14. The bag opening apparatus as defined in claim 1, wherein: the first holding unit includes: a first link which is attached to the first press drive member and swingably supports one side of the support part of the first holding unit, and a second link which is attached to the first press drive member so as to be capable of moving back and forth and swingably supports another side of the support part of the first holding unit, and when the first press drive member presses the first holding unit against the front wall potion, the urging part of the first holding unit urges the contact part of the first holding unit, via the second link and the support part of the first holding unit, in a direction including a component of a direction opposing a direction in which the contact part of the first holding unit is swung.
 15. The bag opening apparatus as defined in claim 1, wherein the contact part includes a second elastic member.
 16. The bag opening apparatus as defined in claim 1, further comprising a pair of grippers which holds both side portions of the bag body, wherein before or while the first press drive member presses the first holding unit against the front wall portion to cause the contact part of the first holding unit to swing, at least one of the grippers is moved in such a manner that a distance between the grippers is reduced.
 17. A bag opening method causing a bag opening apparatus to bend at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap between the front wall portion and the back wall portion, wherein: the bag opening apparatus includes a gap formation unit having: a first holding unit; and a first press drive member which moves the first holding unit between a position where the first holding unit is separated from the front wall portion and a position where the first holding unit is pressed against the front wall portion, the first holding unit includes a contact part, a support part which swingably supports the contact part, and an urging part which urges the contact part via the support part, and the bag opening method includes a step of bending the front wall portion by causing the first press drive member to press the first holding unit against the front wall portion in such a manner that the contact part is swung against urging force of the urging part while the contact part is in contact with the front wall portion. 